1. Field of the Invention
The present invention relates to a liquid crystal display panel, and more particularly to a structure of an upper and lower substrates of the liquid crystal display panel which is cut into an unit panel before a liquid crystal is introduced between the upper and lower substrates integrated with each other. Further, the present invention relates to a manufacturing the liquid crystal display panel which is capable of being cut by a laser light.
2. Description of the Prior Art
Recently, a liquid crystal display (hereinafter, referred to as a LCD) module is widely used as a display unit instead of a cathode ray tube, because of its small size, light weight, and low consumption of power. The LCD module is a plan display unit using a liquid crystal as a light shutter transmitting and screening a transmission of the light, according to the electric signal.
A thin film transistor LCD module (hereinafter, referred to as TFT LCD module) is provided with a TFT substrate, a color filter substrate, and a liquid crystal introduced between the TFT substrate and the color filter substrate. The TFT substrate and the color filter substrate are made of two parent glass substrates which are respectively divided into six LCD panels.
The parent glass substrate which is used for the TFT substrate has a plurality of gate lines, a plurality of data lines which are respectively intersected with each gate line, TFT devices respectively formed at each intersection of the gate lines and the data lines, and pixel electrodes.
Another parent glass substrate which is used for the color filter substrate includes color filter layers respectively having red, green, and blue, a black matrix, and corresponding electrodes. The black matrix prevents a mixture of light in the color filter layers and keeps the thin film transistors from operating in an off-state.
The TFT substrate and the color filter substrate as constructed above are arranged, assembled together and cut along a cutting line into a plurality of the LCD panels before the liquid crystal is introduced between the substrates.
FIGS. 1 and 2 are views showing processes of cutting the integrated substrate by using a diamond scriber and attaching a polarizing plate to the substrate.
Referring to FIG. 1, a method of manufacturing an LCD panel according to the conventional art includes a step ST1 of integrating substrates, a step ST2 of cutting the integrated parent substrates using the diamond scriber, a step ST3 of filling the liquid crystal between the integrated substrates, a step ST4 of sealing a liquid crystal introducing inlet of the integrated substrates, a step ST5 of attaching the polarizing plates to outer surfaces of the integrated substrates, a step ST6 of grinding a cut surface of the substrates using a grinder, and a step ST7 of transferring the substrates to an assembling stage.
Referring to FIG. 2, a method of manufacturing an LCD panel according to another conventional art includes a step of cutting the integrated parent substrates using a diamond scriber, a step of filling the liquid crystal between the integrated substrates, a step of sealing a liquid crystal introducing inlet of the integrated substrates, a step of grinding a cut surface of the substrates using a grinder, a step of attaching the polarizing plates to outer surfaces of the integrated substrates, and a step ST7 of transferring the substrates to an assembling stage.
Regarding methods of manufacturing the LCD panel according to the conventional art, at the grinding step, one of the integrated substrates is cut along cutting lines C1, C2 and G1, and then has been grinded at a predetermined angle at the corner of cut surfaces thereof, as shown in FIGS. 3 and 4. In FIGS. 3 and 4, a reference numeral 14 denotes a short bar connecting gate lines 12 with each other and a reference numeral 16 indicates a short bar connecting data lines with each other. The short bars 14 and 16 discharge the static electricity generated while cutting the substrates.
The grinding step removes glass chips remaining at edges of the substrates from the substrates, prevents damage to a printed circuit board attached to a pad and protects the gate line, the data lines and the panel from cracking.
According to the method referred in FIG. 1, the glass chips around the edges of the substrates generated during the cutting step cause defects in attaching the polarizing plates to the substrates. The defect in the attachment of the polarizing plates forces the polarizing plates to be re-attached, which increases a manufacturing cost.
The method in which the substrate is ground before attaching the polarizing plates as referred in FIG. 2 may remarkably reduce defects in the polarizing plate attachment. However, the removal of the short bar 14 from the substrates cut along the cutting line G1 as shown in FIGS. 3 and 4, causes malfunction of the panel's TFTs due to the static charges due to a friction during the grinding step.
Referring to FIG. 3 again, the cutting of the parent substrate using the laser light starts at an outer surface of the substrate. The parent glass substrate can be cut along the cutting lines, but the interconnection lines 12 formed on an inner surface of the substrate are occasionally not cut. As shown in FIGS. 5a and 5b, even though the parent glass substrate 10 is exactly cut along the cutting lines C1 and C2, the crack generated in the parent glass substrate 10 may not be transferred to the interconnection lines 12 disposed on the inner surface of the substrate and the interconnection lines 12 are not exactly cut.
It is considered that the cutting problems are caused by the ductility and heat expansion difference of metals used for the interconnection lines.
Sealant is coated on the inner surface of one substrate in order to integrate the substrates together.
FIG. 6 is a view showing the sealant coated on the substrate, the liquid crystal introducing inlet 37, and the cutting line 39a on the substrate according to the present invention. Reference numerals 38a, 38b, 39a, and 39b respectively denote the cutting line and reference numeral 34 indicates the black matrix.
Referring to FIG. 6, a seal line formed on the substrate, except for the liquid crystal introducing inlet is not overlapped with the cutting line. However, a part of the seal line forming the liquid crystal introducing inlet extends across the cutting line 39a. Therefore, since the cutting line 39a near the liquid crystal introducing inlet 37 is cut under a cutting condition different from another cutting lines, it is difficult to cut the integrated substrate into a plurality of panels by laser. Thus, different cutting conditions for the portion near the liquid crystal introducing inlet and for the rest of the substrate have to be set up, which complicates the cutting process.
As shown in FIG. 12, in the case that the cutting line 39a extends across a neck portion of the liquid crystal introducing inlet 37, there is a problem in that when the sealant 66 is supplied to close the liquid crystal introducing inlet 37, air is introduced through the liquid crystal introducing inlet 37 into a liquid crystal layer between the integrated substrate 32.